INSTALLATION is as follows;

[Vehicles]

1. Start OpenIV.
2. Go to the 'mods' folder, create one if you don't have one.
3. Drag the lsiapd folder to mods\update\x64\dlcpacks
4. Find dlclist.xml - It's located here mods/update/update.rpf/common/data
6. Edit the dlclis.xml and add <Item>dlcpacks:\lsiapd\</Item> at the bottom

[EUP]

As for the EUP installation, it's pretty self explanitory. Open up the eup archive, located here - \mods\update\x64\dlcpacks\eup\dlc.rpf\x64\eup_componentpeds.rpf and drop the folders in there.

The plugins folder which contains presetoutfits should be placed in the main directory.